The present invention relates to irrigation sprinklers and pertains particularly to an proved sprinkler riser damping means.
Irrigation as a means to provide water to plant life has been used for hundreds, if not thousands of years, and is still in wide use throughout the world today. One of the most widely used systems, particularly for lawn areas and playing or athletic fields, is the underground sprinkler system wherein a plurality of sprinkler units are positioned about a land area for distributing water over the surface of the land area. One of the most popular sprinkler units currently in use is a retractable gear driven rotary head that rotates about a generally vertical axis and covers either an arc segment or a full circle. Such units employ a water driven turbine connected through a reduction drive gear train to the sprinkler head in which a nozzle is mounted to direct a stream of water outward in an arc or circle about the rotary axis of the sprinkler unit.
Sprinkler units of this type, particularly larger units are widely used in irrigation systems used on golf courses and other turf applications. These systems are usually high pressure so that the sprinkler units are frequently subjected to extreme forces over their lifetime of use which can damage them and reduce their useful life. The most serious of these forces result from water hammer and high pressure surges that occur during system winterization and spring recharge. These high forces are especially prevalent when empty pipes are being filled with water. Slugs of water accelerate down the length of the pipe, and pops open the valve in the bottom of the sprinkler body and slams the riser including the rotor up to the end of its stroke against the top of the housing. Due to the pressures and large pipe sizes for large turf applications, these forces can be extremely high and frequently cause failure of the rotors. Attempts to solve this problem by making the sprinkler housing and parts heavier and stronger have been unsatisfactory because of increased costs. The dual medium of water and air has prevented the use of slow opening valves that use the control of the flow of the fluid from being successful. Accordingly, there is a need for simple and effective means for reducing or eliminating the above described forces to provide longer life sprinkler units.
Accordingly, there is an evident need for a sprinkler unit having means for reducing or eliminating the aforementioned forces to provide longer life sprinkler units.